1. Field of the Invention
The present invention relates to a liquid pumping apparatus, and more particularly, relates to a liquid pumping apparatus for pumping a liquid, such as chemicals or blood etc. into a human body by revolving rollers rotated by a prime mover to compress a flexible tube to thereby force the liquid through the flexible tube.
2. Description of the Prior Art
A liquid pumping apparatus, wherein a flexible tube is inserted into a clearance formed between a fixed inner periphery wall and revolving rollers to compress the flexible tube and thereby force a liquid through the flexible tube is described in the Japanese Patent Application Laid-Open No. 268887/86, for example.
However, in such prior art, it is necessary to slowly insert the flexible tube into the clearance while rotating a rotor having the rollers, because the clearance is so small that the flexible tube is collapsed fully. Accordingly, installation of the flexible tube requires an undesirable amount of time and labor.
Further, it is necessary to use a large force for removing the flexible tube from the small clearance formed between the fixed inner periphery wall and the revolving rollers, so that the flexible tube is liable to be damaged.
In case that guide rollers are provided on the outer peripheral surface of the rotor in order to guide the flexible tube in a moving path of the rollers, the flexible tube is contacted and damaged by the guide rollers when the flexible tube is inserted into the clearance.